A connection with liver cancer with infection by Hepatitis B virus (HBV) and use of interferone or a nucleoside analogue for treating the HBV infection, have been reported. However, such treatment has been applicable only for some of the infected patients and could not remove HBV completely. Therefore, there is a need for substrate materials to enhance the curative efficiency against HBV infection.
Studies for finding intracellular factors which bind to HBVPol have been well advanced, and Pol of duck hepatitis B virus, which binds to Hsp90, p23 and Hsp70, shows a possible important role in the virus growth (Hu, J. et al., Hepadnavirus assembly and reverse transcription require a multi-component chaperone complex which is incorporated into nucleocapsids, EMBO J., 16 (1997) 59–68). Although this research was not carried out on HBV capable of infecting humans, HBVPol with multiple enzymatic activities as a single protein, has high possibility of binding intracellular factors and is believed to complete the multiple enzymatic activities through such processing.
HBVPol is expressed in a very low level in E. coli or yeast so that biochemical and structural research therefor are not feasible. For this reason, the live viruses have been used or experiments through in vitro eukaryotic expression have been performed. However, these experiments pose a danger according to how they are conducted and the consequent performance thereof involves high costs required to carry them out safely.